To determine whether homocyst(e)ine, a relatively new risk factor for possible endothelial cell dysfunction and premature vascular disease, is elevated in nulliparous pregnant women with preeclampsia, we measured plasma homocyst(e)ine, folic acid and vitamin B-12 levels in 40 nulliparas, 20 with and 20 without preeclampsia at the time of their delivery. Mean ( standard deviation) plasma homocyst(e)ine levels in the 20 nulliparous women with preeclampsia were significantly higher than in the 20 nulliparous women without preeclampsia (8.66 3.05 versus 4.99 1.11 mol/L, P<.001). Folic acid and vitamin B-12 concentrations were not significantly different between the two groups. Homocyst(e)ine levels are elevated in pregnant nulliparas with preeclampsia at the time of their delivery. Further studies are necessary to determine what role homocyst(e)ine may play in the etiology of preeclampsia.